Changes in particulate matter concentrations at different altitudinal levels with environmental dynamics
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Zulfiqar Ali , Safdar Sidra , Nimra Afzal , Khadija Aziz , Zaidi Zona , Irfan Zainab , Syed Turab Raza ,
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Mubashir Ahmad , Bushra Ansari , Quratulain , Zaheer Ahmad Nair , Ian Colbeck
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Environmental Health and Wildlife, Department of Zoology, University of the Punjab, Lahore, Pakistan
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Department of Civil, Environmental and Geomatic Engineering, University College London, UK
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School of Biological Sciences, University of Essex, Colchester, UK
Corresponding author: dralizulfiqar@gmail.com
Summary: PM levels show varying trends at different altitudes and are greatly affected by meteorological parameters
as well. The current study was designed to monitor ambient PM levels at seven locations of Pakistan with varying
altitudes from zero (Sea level) up to 3189 metres. Highest PM levels were observed at Sari Lake with an elevation of
3189 m which is in contrast with many other studies. More research needs to be conducted to completely understand
the phenomenon ruling the formation and dispersion of PM at different altitudes.
Introduction: Ambient air pollution is responsible for 1.3 million deaths per year. Persistent daily exposure to
particulate matter results in increased mortality rates resulting from various respiratory and cardio-pulmonary
diseases such as pneumonia, asthma, chronic obstructive pulmonary disease and many others. According to WHO
(2014), Pakistan is among the worst polluted countries; with an annual average level of fine particulate matter to be
as high as 101µg/m³ and that of PM10 to be 282µg/m³.
Methodology: Seven locations, each present at different elevation from sea level, were selected from all over
Pakistan for monitoring of PM2.5. DustTrak DRX (Model 8533, TSI Inc.) was employed for twenty four hours real time
monitoring of particulate matter at the selected sites.
Results and Discussion: In the current study, ambient concentrations of PM were monitored at seven different
locations of Pakistan present at varying altitudes. A considerable variation was observed in 24 hour trend of PM at
different locations (Table 1) owing to variation in meteorological conditions, and natural and anthropogenic sources in
the vicinity. The highest average concentrations of 405.17µg/m³ were observed at highest elevation (Sari Lake,
Shogran, 3189 m) while lowest averages (102.47 µg/m³) were obtained at seaside (Hawks Bay, Karachi, 0
m).Transport of aerosols is affected by turbulence caused by thermal-dynamic property of the air. Although there is
still not sufficient data on behaviour of fine particulate matter at different elevations, many studies have documented
observed lower PM levels at higher elevations. Moreover the concentrations were lower during the colder months and
increased significantly during the summers due to more rapid dispersal facilitated by thermal buoyancy. Our results
are in contract to the above mentioned studies and more research needs to be conducted in this context. Moreover
the effect of meteorological parameter should also be considered as formation of CAPs at higher altitudes can affect
pattern of particulate dispersal in the atmosphere.
Table 1: Mean levels of PM2.5 monitored at different sites in Pakistan
SITE & ELEVATION
KARACHI ( 0 m)
TAUNSA (136 m)
LAHORE (174 m)
MIRPUR (352 m)
PIR SUHAWA (1232 m)
KHANSPUR (2204 m)
SARI LAKE (3189 m)
MAX
342
1580
660
882
407
393
2660
MIN
PM2.5 (µg/m³)
AVERAGE
35
102.47
109
367.74
65
181.15
237
306.36
53
104.09
49
106.03
378
405.17
STDEV
86.09
235.81
81.5
51.02
60.29
29.01
53.78
References:
WHO (2014). Ambient (outdoor) air pollution in cities database 2014. Retrieved from:
http://www.who.int/phe/health_topics/outdoorair/databases/cities/en/
Silcox, G. D., Kelly, K. E., Crosman, E. T., Whiteman, C. D., and Allen B. (2012). Wintertime PM2.5 concentrations
during persistent, multi-day cold-air pools in a mountain valley. Atmospheric Environment. 46: 17-24.